Seventy-one subjects (22 English monolinguals, 23 Spanish monolinguals, and one bilingual group comprised of 19 Spanish-dominant and 7 English-dominant bilinguals) were assessed by means of the Woodcock-Johnson Psycho-Educational Battery and the Woodcock-Johnson Language Proficiency Battery at the beginning of kindergarten and first grade. These instruments were used to measure oral language, reading aptitude, and reading ability. Results helped to establish patterns of language dominance in the bilinguals and to define different aspects of language proficiency in terms of semantic functioning (i.e., defining words and understanding relationships between words) and communicative competence in everyday activities. It was found that when tested in their weaker language, bilingual children fell behind in basic reading ability and, in the case of early reading in English, group differences were more related to differences in language proficiency and lack of formal English instruction than to differences in cognitive ability and home experience. Results also show that Spanish monolinguals acquire some proficiency in English but at levels below those of other groups. A list of 27 references is included. (Author/MSE)